J/ApJ/869/171 Chandra observations of NuSTAR sources (Tomsick+, 2018)
Chandra observations of NuSTAR serendipitous sources near the Galactic plane.
Tomsick J.A., Lansbury G.B., Rahoui F., Aird J., Alexander D.M., Clavel M.,
Cuturilo A., Fornasini F.M., Hong J., Klindt L., Stern D.
<Astrophys. J., 869, 171 (2018)>
=2018ApJ...869..171T 2018ApJ...869..171T
ADC_Keywords: Active gal. nuclei; X-ray sources; Galactic plane; Positional data
Keywords: stars: black holes ; stars: neutron ; surveys ; white dwarfs ;
X-rays: stars
Abstract:
The Nuclear Spectroscopic Telescope Array (NuSTAR) serendipitous
survey has already uncovered a large number of active galactic nuclei
(AGNs), providing new information about the composition of the cosmic
X-ray background. For AGNs off the Galactic plane, it has been
possible to use existing X-ray archival data to improve source
localizations, identify optical counterparts, and classify the AGNs
with optical spectroscopy. However, near the Galactic plane, better
X-ray positions are necessary to achieve optical or near-IR
identifications due to the higher levels of source crowding. Thus, we
have used observations with the Chandra X-ray Observatory to obtain
the best possible X-ray positions. With eight observations, we have
obtained coverage for 19 NuSTAR serendips within 12° of the plane.
One or two Chandra sources are detected within the error circle of 15
of the serendips, and we report on these sources and search for
optical counterparts. For one source (NuSTAR J202421+3350.9), we
obtained a new optical spectrum and detected the presence of hydrogen
emission lines. The source is Galactic, and we argue that it is likely
a cataclysmic variable. For the other sources, the Chandra positions
will enable future classifications in order to place limits on faint
Galactic populations, including high-mass X-ray binaries and
magnetars.
Description:
As we are focusing on Galactic sources, these observations target
Nuclear Spectroscopic Telescope Array (NuSTAR) serendips within
12° of the Galactic plane.
Table 1 lists the Chandra observations that we used for this work. We
obtained seven of the pointings as part of our Chandra Guest Observer
(GO) programs from cycle 16 and 17, and these were carried out with
the aimpoint (the center of the field of view) on the Advanced CCD
Imaging Spectrometer (ACIS-S CCD) chip. We also used one additional
ACIS pointing (ObsID17704) from the Chandra archive. These
observations were all made during 2015 and 2016 with exposure times
ranging from 4.9 to 28.8ks.
In addition to the primary target, the Chandra observations cover
other NuSTAR serendips because of the similar sizes of the Chandra and
NuSTAR fields of view, and Table2 lists the 19 serendips for which
Chandra coverage was obtained.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 8 Chandra observations
table2.dat 46 19 NuSTAR serendips studied in this work
table4.dat 71 25 Chandra candidate matches to NuSTAR serendips
table7.dat 68 209 Chandra sources in NuSTAR serendip fields
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey Galactic HI (Kalberla+,2005)
J/ApJ/635/214 : Chandra X-ray sources and NIR identifications (Ebisawa+, 2005)
J/ApJ/749/21 : AGNs detected by 60 month Swift/BAT survey (Ajello+, 2012)
J/ApJ/808/184 : NuSTAR surveys: ECDF-S catalog (Mullaney+, 2015)
J/ApJ/825/132 : NuSTAR hard X-ray survey of Galactic Center. II. (Hong+, 2016)
J/ApJS/223/15 : 8yr INTEGRAL/IBIS soft gamma-ray source obs. (Bird+, 2016)
J/ApJ/836/99 : NuSTAR serendip. survey: the 40-month catalog (Lansbury+, 2017)
J/ApJS/235/17 : NuSTAR Extragalactic Surveys: UDS field (Masini+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ObsID [17245/18089] ObsID of the target
7-12 F6.2 deg GLON [10/322] Galactic longitude (J2000)
14-19 F6.2 deg GLAT [-12/12] Galactic latitude (J2000)
21-31 A11 "Y/M/D" Obs.date Starting (UT) date of observation
33-37 F5.2 h Obs.time Starting (UT) time of observation;
in decimal hours
39-43 I5 s Exp [4939/28755] Exposition time
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- --- [NuSTAR]
8-21 A14 --- NuSTAR Name of the serendipitous source (JHHMMSS+DDMM.m)
23-26 A4 --- L17 Name in the L17 catalog ([PS]NNN) (1)
28-36 F9.5 deg RAdeg [195/320] Degree of right ascension (J2000)
38-46 F9.5 deg DEdeg [-64/34] Degree of declination (J2000)
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Note (1): "P"= Primary catalog (Table 5), "S"=Secondary (Table 7)
in Lansbury+, 2017 J/ApJ/836/99 (<NuSTAR JHHMMSS+DDMM.m> in Simbad)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1 -5 I5 --- ObsID [17245/18089] ObsID of the target (1)
6 A1 --- --- [-]
7 -8 I2 --- Seq [1/28] Sequence number within ObsID (1)
10-25 A16 --- CXOU CXOU name of the target (JHHMMSS.s+DDMMSS)
27-28 I2 h RAh Chandra Hour of right ascension (J2000)
30-31 I2 min RAm Chandra Minute of right ascension (J2000)
33-37 F5.2 s RAs Chandra Second of right ascension (J2000)
39 A1 --- DE- Chandra Sign of declination (J2000)
40-41 I2 deg DEd Chandra Degree of declination (J2000)
43-44 I2 arcmin DEm Chandra Arcminute of declination (J2000)
46-49 F4.1 arcsec DEs Chandra Arcsecond of declination (J2000)
51-54 F4.2 s ePos [0.7/4.3] 90% confidence uncertainty on the
position (G1)
56-61 F6.1 --- Ncts [4/4142] Number of ACIS counts detected (G2)
63-66 F4.1 --- e_Ncts [3/66] Ncts uncertainty
68-71 A4 --- L17 Name in the L17 catalog ([PS]NNN) (2)
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Note (1): The sources are identified by ObsID and the Chandra source number
from the full source list (Table 7).
Note (2): If the Chandra source falls within the error circle of a NuSTAR
serendipitous source, then this indicates the number of the NuSTAR
serendipitous source in the L17 (Lansbury+, 2017 J/ApJ/836/99) catalog.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1-5 I5 --- ObsID [17245/18089] ObsID of the target
7-8 I2 --- Seq [1/47] Running sequence number within ObsID
10-14 F5.2 arcmin Sep [0.09/47] Angular distance between the Chandra
aimpoint and the source (Θ)
16-17 I2 h RAh Hour of right ascension (J2000)
19-20 I2 min RAm Minute of right ascension (J2000)
22-26 F5.2 s RAs Second of right ascension (J2000)
28 A1 --- DE- Sign of declination (J2000)
29-30 I2 deg DEd Degree of declination (J2000)
32-33 I2 arcmin DEm Arcminute of declination (J2000)
35-38 F4.1 arcsec DEs Arcsecond of declination (J2000)
40-43 F4.2 arcsec ePos [0.7/8.5] Error on position (G1)
45-50 F6.1 --- Ncts [3/5213] Number of ACIS counts detected (G2)
52-55 F4.1 --- e_Ncts [3/74] Ncts uncertainty
57-68 A12 --- OID ? Other identification(s) (1)
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Note (1): There is an entry in this column if the Chandra source may be
identified with another source. The identifications may be names of
NuSTAR serendips, names of known sources, or names of catalogs if we
simply identified the Chandra source with a source in an optical or
near-IR catalog.
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Global notes:
Note (G1): The 90% confidence uncertainty on the position, including statistical
and systematic contributions.
Note (G2): The number of ACIS counts detected (after background subtraction) in
the 0.5-7keV band (except for ObsID17704, for which the energy band
is 2-7keV). The errors are 68% confidence Poisson errors using the
analytical approximations from Gehrels 1986ApJ...303..336G 1986ApJ...303..336G
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History:
From electronic version of the journal
(End) Coralie FIX [CDS] 14-Nov-2019